Halogenated compounds and climate change: future emission levels and reduction costs

OBJECTIVES: This work assesses the contribution to climate change resulting from emissions of the group of halogenated greenhouse gases. METHODS: A bottom-up emission model covering 22 technological sectors in four major regions is described. Emission estimates for 1996 and projection for 2010 and 2020 are presented. The costs for deep cuts into projected emission levels are calculated. RESULTS: The substances covered by this study have contributed emissions of 1100 +/- 800 MT CO2 equivalents per year in 1996. In terms of their relative contribution to emissions of CO2 equivalents, this corresponds to 3 +/- 2% of global emissions of all anthropogenic greenhouse gases. The wide range of uncertainty is due to the poorly quantified net global warming potential of the ozone depleting substances, which have an indirect cooling effect on climate through the destruction of stratospheric ozone. For annual emissions of HFCs, PFCs and SF6 (which are regulated under the Kyoto Protocol and for which global warming potentials are well defined), the relative contribution is projected to increase to 2% (600 MT CO2 eq.) of global greenhouse gas emissions by 2010. This trend is expected to continue, emissions are projected to grow to a contribution of roughly 3% (870 MT CO2 eq.) in 2020 compared to 0.9% (300 MT CO2 eq.) in 1996. For HFCs, PFCs and SF6, this study identifies global emission reduction potentials of 260 MT CO2 eq. per year in 2010 and 640 MT CO2 eq. per year in 2020 at below US$ 50 per ton. These values correspond to roughly 40% and 75% of projected emissions in 2010 and 2020, respectively.